The finely laminated sediment record of a permanent, hypersaline, desert oasis lake in the Ounianga region of northeastern Chad presents a unique opportunity to document the hydrological evolution of this groundwater-fed aquatic ecosystem during mid- and late-Holocene desiccation of the Sahara. In this study we reconstruct long-term changes in zoobenthos and zooplankton communities of Lake Yoa as their early-Holocene freshwater habitat changed into the hypersaline conditions prevailing today. Chironomid...

The Lake Yoa record and archaeological data provide adequate evidence that mid-Holocene
aridification did not occur abruptly across all of North Africa. Modeling results on the
issue of abrupt versus gradual desiccation of the Sahara are sufficiently diverse that paleoecological
data from a continuous natural archive can usefully guide the evaluation of model parameters
responsible for this diversity.

Lake Yoa (19.03°N, 20.31°E, 380 m a.s.l.) is a groundwater-fed lake in the hyperarid
eastern Sahara halfway between the Tibesti Mountains and the Ennedi plateau.
Kröpelin et al. (2008) revealed that the bottom sediments contain a unique archive of
climatic and environmental change in the Earth´s major desert. The 7.5 m sediment
record of OUNIK03/04 which covers 6,100 years has been extended to a maximum
drill depth of 15.7 m during a 2010 coring campaign within the framework of the
Collaborative...

The sedimentological and geochemical properties of a 7.47 m long laminated sequence from hypersaline Lake Yoa in northern Chad have been investigated, representing a unique, continuous 6100 year long continental record of climate and environmental change in the eastern Central Sahara. These data were used to reconstruct the Mid to Late Holocene history of this currently hyper-arid region, in order to address the question of whether the Mid Holocene environmental transition from a humid to a dry Sahara was...